Voluminous yarn from synthetic continuous thermoplastic filaments



T. D. BETSCH 3,142,147 vowumous YARN? FROM smmz'rrc commons THERMOPLASTIC FILAMEms Original fil'xdv arch 9, 1959 July 28, 1964 4- Sheets-Sheet FIG-1 T'hieodiome Df ch ATTORNEY July 28, 1964 3,142,147

T. D. BETSCH VOLUMINOUS YARN FROM SYNTHETIC CONTINUOUS THERMOPLASTIC FILIMEQTS Original Filed March 9, 1959 4 Sheets-Sheet 2 INVENTOR. Theo do m D. Bets ch July 1964 vowuxuoljs ym r i ioe szfizsm uc commuous 3'142147 'H-IERIOPLASTIC FILMIENTS Original Filed larch 9, 1959 4 Sheqts-Shoot 3 Q 25 (u) I I6 5 54 HOTGAS INVENTOR. Theodore D.Bctsch lid T ATTORNEY y 23, 1964 T. D. BETSCH 4 VOLUMINOUS YARN FROM SYNTHETIC CONTINUOUS THERMOPLASTIC FILAMENTS Original Filed larch 9,-1959 4 Sheets-Sheet 4 PRIOR ART FIG. 5

INVENTOR. Theodore D.Betsch ATTORNEY United States Patent C) signments, to Monsanto Company, a corporation of Delaware Original application Mar. 9, 1959, Ser. No. 798,163. Divided and this application Dec. 13, 1960, Ser. No.

2 Claims. (Cl. 57-140) This invention relates to the manufacture of voluminous texturized yarn and particularly relates to synthetic continuous filaments made from thermoplastic resins and exhibiting a wooly, fiuify, stretchable character.

This application is a division of copending application, Serial No. 798,163, filed March 9, 1959.

Synthetic textile yarns are classified generally into two distinct types, each having its own properties and advantages. One type known as spun yarn is spun from synthetic textile staple fibers. Among other things, the spun yarns have the disadvantage of relatively low strength. However, some of the advantages associated with spun yarns include enhanced capacity to absorb moisture, greater insulating power, a more agreeable hand, and a toned-down luster. The other type of synthetic textile yarn is known as continuous filament yarn. While continuous filament yarns have the advantage of greater evenness and superior strength, they have several undesirable properties including low heat insulating values, lack of bulkiness desired for some end uses, and low covering power.

Many attempts have been made in the past to impmt some of the desirable properties of spun yarn to continuous filament yarn. Along this line a process recently has been developed where a continuous filament yarn is treated in such a way that the resulting yarn possesses in combination some of the properties characteristic of filament yarn and some of the properties characteristic of spun yarn. This combination of the intrinsic properties of the two distinctly diiferent types of yarns into one yarn confers on the resulting yarn increased covering power and its own particular structure and hand. The known yarn possessing this combination of properties is best characterized by the fact that individual filaments thereof have been convoluted into coils or loops at random intervals along their lengths. The principle underlying the manufacture of the new voluminous yarn is based on the displacement of the filaments in a strong current of air or gas, as the result of which filament loops project outwardly from the body of the filaments. This filamentary displacement is accomplished by passing a continuous filament yarn into a confined zone through which a stream of high velocity gas is passed and abruptly removing the yarn from the stream of gas just as the yarn is withdrawn from the zone.

While the loops in the filaments impart several characteristic arid desirable properties to continuous filament yarn as indicated above, the physical or chemical properties of the yarn stock are not fundamentally altered by the air treatment. Briefly stated, all that happens is that the filaments are disarranged by the agitation of the blast of air in such a manner that the loopy structure as mentioned above results. When processing the yarn having the loops, it is necessary to bear in mind that this yarn is snared easily owing to the projecting loops. Hence, this tendency of the new loopy yarn to catch is likely to be particularly troublesome in processing same into fabric and other textile articles. While a suitable sizing agent may be used to overcome this problem to some extent, such solution to the problem obviously adds to the cost of the process. Furthermore, it is necessary to avoid subjecting the loopy yarn to high tensions and it is best to keep the 3,142,147 Patented July 28, 1964 tension as even as possible. When sufficient tension is applied to the yarn, the loops are removed permanently. It has been found that only slight tension is necessary to effect loop removal when the yarn has little or no twist. While the loops are more permanent when they are held by twist, twisting operations are expensive and time com suming; and a twisted yarn is less voluminous and has reduced covering power. Moreover, the lateral interfilament spacings of the yarn, containing the projecting loops are not as sufiicient as would be desirable and such yarn has little or no stretchability.

An object of this invention is to provide a simple, rapid, and economical method for commercially producing a thermoplastic continuous filament y-arn having a wooly, fiuffy, stretchable character and possessing many properties associated with spunyarn while retaining many properties associated with filament yarn, such as strength. Another object of this invention is to provide a method of imparting greater bulk and stretchability to a bundle of synthetic thermoplastic continuous filaments by displacement and deformation of the filaments by a strong current of gas, the resulting yarn having enhanced flufiiness without the loops associated with yarn displaced by compressed gas in accordance with the prior art methods. Still another object of this invention is to provide an efiicient apparatus with which thermoplastic continuous filament yarn can be quickly and economically treated so as to impart thereto enhanced bulkiness, substantially permanent crimpiness, and other desirable properties, the treated yarn producing a thicker and more capacious textile article when woven, knitted, tufted, etc., for a given weight of yarn. A further object of the present invention is to provide an improved voluminous thermoplastic continuous filament yarn which is vastly different in appearance from the yarn heretofore obtained by the art, characterized particularly by the fact that the filaments thereof have been simultaneously disturbed and thermally deformed by a stream of high velocity gas in a dry state. A further object of the present invention is to provide a novel, bulky yarn composed of synthetic thermoplastic continuous filament yarn, the cross-sections of the filaments having been modified from the normal circular cross-section.

Other objects and advantages of the present invention will become apparent from a study of the following specification, claims, and drawing. Preferred embodiments of apparatus for preparing the new yarns of this invention will now be described with reference to the accompanying drawing wherein:

FIGURE 1 is a schematic view in elevation, with principal parts in location, illustrating one arrangement of apparatus suitable for preparing the new voluminous yarns;

FIGURE 2 is a schematic view in perspective with prin cipal parts in location, illustrating a second arrangement of apparatus suitable for preparing the new voluminous yarns;

FIGURE 3 is a schematic view in elevation with principal parts in location illustrating a third arrangement of apparatus suitable for preparing the new voluminous yarns;

FIGURE 4 is a drawing of nylon yarn treated in accordance with the prior art method of imparting bulk to continuous yarn by air disturbance, showing the projecting loops associated therewith;

FIGURE 5 is a drawing of nylon yarn treated in accordance with the present invent-ion showing its fluffy, crimpy, voluminous character and further illustrates the substantial absence of loops and the pronounced lateral spacing of the individual filaments; and

FIGURE 6 is a considerably enlarged view of a single filament of Y-shaped cross-section treated in accordance with the present invention, illustrating the randomly reversed helical twist therein.

In the continuous filament yarn voluminizing apparatus shown schematically in FIGURE 1 the thermoplastic yarn indicated by numeral 10, such as nylon and the like, composed of a bundle of smooth continuous filaments is withdrawn from a yarn source, for example yarn package 11, and is passed upwardly over one end of bobbin 12 or other yarn holder, such as a pirn or cone. The yarn is threaded through a tensioning device 13, for example the gate type as illustrated, that is preferably disposed directly over the yarn package 11. From the tensioning device 13 the yarn 19 is passed in an upward direction between a thread advancing means 14 that supplies the yarn at a controlled supply rate and which is operated at a first peripheral speed and comprises as illustrated a pair of driven feed rolls. From means 14 the yarn It) is led diagonally upwardly to a fluid jet generally designated by numeral 15 and adapted to receive the yarn. This jet is provided with a diagonally extending side arm 16 having a central bore into which the yarn is passed and is provided also with a longitudinal axial bore establishing communication with the bore in arm 16.

A compressor 17 is employed to maintain a compressible gas in a reservoir or storage tank 18 under a predetermined elevated pressure sumcient so that a stream of high velocity gas can be supplied to jet 15 as desired. The storage tank 18 is connected by conduit 29 to heating zone or heating chamber 21 through which the compressed gas is directed on its way to jet 15. As shown, chamber 21 is provided with an electrically energizable heater element 22, electrical power being supplied to said element 22 through conductive lines 23 having a terminal plug 24 adapted for reception in a power outlet source. Obviously, other similar heating arrangements, such as internal or external heating plates and the like, can be used. Moreover, chamber 21 can have heat supplied to it externally, such as provided by proper arrangement of a combustible gas or liquid burner. However, since electrically powered heating means can be used with great convenience, such means are of course preferred. In chamber 21 the compressed gas is heated to an elevated temperature and the temperature of the gas leaving the exit end of said chamber is maintained at a uniform temperature by a thermostat arrangement, not shown. After being heated the compressed air is led to jet 15 through an insulated conduit 25. Valve 26 in the inlet end of jet 15 is ordinarily opened before threading of the yarn through the jet since the movement of the gas upwardly through the horizontal bore thereof will assist in doing this. Near the central portion of jet 15 the yarn contacts the gas and is propelled concurrently thereby. While traveling with the heated gas the thermoplastic filament yarn becomes heated to an elevated temperature, sufiiciently high that if the thermoplastic yarn were twisted at this point and cooled in the resultant twisted condition, the twist would be set. Therefore, it is seen that care must be exercised to maintain the proper correlation between air pressure, heat, speed, yarn size, and other process variables. The yarn is conveyed through the upper part of jet 15 by the gas flowing at a high velocity therethrough. As can be seen, the yarn initially contacts the flowing stream of gas at an angle with respect to the directional flow of the gas and, in particular, at an acute angle with respect to the upstream flow of the gas. However, this particular angular engagement is not essential to the invention. For example, the jet may be constructed so that the yarn passes in a straight line longitudinally through the jet with the hot compressed gas initially contacting the yarn at an angle with respect to the path of yarn travel.

Upon leaving the upper end of jet 15 the thermoplastic yarn is withdrawn at an angle with respect to the flow of the gas as soon as it emerges therefrom. Preferably, the angle of withdrawal is substantially 90, i.e., at a right angle with respect to the flow of gas, whereby the heated yarn is removed abruptly from the influence of the gas. The abrupt removal of the yarn from the stream of gas is accomplished by proper positioning of a guide, such as pigtail guide 27 or the like, horizontally spaced from the upper end of the jet, and by passing the yarn therethrough. A second yarn guide, as for example, pigtail guide 23, is disposed above guide 27. A traverse guide 34 and a yarn take-up holder 31 surface driven by roll 32 completes one position of the apparatus illustrated in FIGURE 1. As can be seen the yarn is led through guides 27 and 28 and thence through the traverse guide which lays the yarn on holder 31 to form a uniform package 33 without increasing the twist of the yarn. The peripheral speed of roll 32 is less than the linear speed at which the yarn is supplied to the jet by means 14 in order to compensate for the induced bulkiness of the yarn. In other words, arrangement is made that the speed of ingress of the yarn to the jet is more than the speed of egress therefrom. Before the yarn is taken up in package form, it is cooled by being passed through the atmosphere.

The above-described mechanism produces bulked, highly crimped, stretchable continuous filament yarn (see FIGURE 5) made from various thermoplastic polymers. Since the increased bulk and crimp are induced by the disturbance and discomposure of the filaments under the application of very hot dry air and cooled in the resulting disarrangement, the enhanced bulky character and crimp of the yarn are highly stable.

While one yarn treating unit is illustrated in FIGURES 1, 2, and 3, it will be appreciated readily that the apparatus of the instant invention may be provided with a plurality of identical yarn possessing units along its length. However, a single source of heated compressed gas can be used to supply a plurality of jets. Moreover, yarn from two or more different sources which may or may not be of the same thermoplastic material or have the same denier, twist, or other properties can be combined by feeding same together through the jet.

Reference is now made to FIGURE 2 where another embodiment of the invention is shown in which the means for compressing and heating the dry gas have been omitted with the insulated conduit for supplying the hot gas to the jet, however, being shown in part. Thermoplastic yarn It), such as nylon and the like, composed of a bundle of cold-drawable smooth continuous filaments is withdrawn from a yarn package 11 and is passed over one end of bobbin 12 or other yarn holder. Then the yarn is passed through a pigtail guide 34 or similar guide means. From this yarn guide the yarnis passed in a downward direction between a thread advancing means 35 operated at a first peripheral speed and comprising as illustrated a pair of driven feed rolls. From means 35 the yarn is wrapped a few times around a stationary snubbing bar 36 and then around roll 37 and spacer bar 38. In operation roll 37 is rotated at a predetermined greater peripheral speed than the peripheral speed of thread advancing means 35, thereby imparting a predetermined stretch to the yarn. Hence, a continuous yarn, such as nylon which has not been drawn fully to orient same, can be stretched continuously immediately prior to being subjected continuously to the hot dry air disturbance according to this invention, thereby resulting in more economical overall yarn processing.

Jet 15 is positioned so that its longitudinal axial bore through which the dry compressed air passes is disposed horizontally and spaced diagonally from roll 37 so that yarn it can be fed conveniently into arm 16 of the jet. It will be perceived that the angular disposition of the jet is not critical and will be determined to a great extent by the position of the means for feeding and withdrawing the yarn to and from the jet. Heated dry gas flurrying or flowing at a high velocity horizontally through the jet conveys the yarn therethrough and heats the same as desired. Again as shown, the thermoplastic yarn initially contacts the flowing stream of hot gas at an angle with respect to the directional flow of the gas. Upon leaving the exit end of jet 15 the yarn is withdrawn abruptly at an angle with respect to the flow of the gas as soon as it emerges therefrom. The abrupt angular removal of the yarn from the stream of gas is accomplished by proper positioning of a guide. Since care must be exercised to maintain a controlled yarn withdrawal speed from the jet, that is the speed at which the yarn is withdrawn from the jet must be at a reduced speed as compared to the speed at which the yarn is fed to the jet in order to compensate for the induced bulkiness, one can employ a driven thread advancing means 40, such as a pair of feed rolls as illustrated, for accomplishing this and for proper guiding of the yarn emerging from jet 15. The yarn is then taken up in an orderly and conventional manner. As shown, the yarn is passed through pigtail guide 41 and then is taken up by a ring twisting assembly 42 which comprises a bobbin 43 adapted to be rotated by driven belt 44 in a conventional manner and to collect a supply of the yarn indicated by reference numeral 45. The assembly also comprises a conventional spinning ring 46 carrying a ring traveller 47 adapted to rotate about the bobbin 43 as the yarn is twisted a desired amount and wound on the bobbin.

Reference is now made to FIGURE 3 where a further embodiment of the invention is exemplified in which the means for compressing and heating the dry gas have been omitted with the insulated conduit 25 for supplying the hot gas to the jet, however, being shown in part- Thermoplastic continuous filament yarn It; is withdrawn from a yarn package 11 and is passed over one end of bobbin 12 or other yarn holder. Then the yarn is passed through a pigtail guide and is fed to side arm 16 of jet 15 at a controlled speed by a thread advancing means 59, such as the feed rolls illustrated. Although not illustrated, it wi l be appreciated that the yarn can be oriented in accordance with the embodiment jsut described above by drawing same before the yarn enters jet 15.

Jet 15 is positioned so that its longitudinal axial bore through which the dry compressed air passes is disposed horizontally and spaced diagonally from rolls 49 so that the yarn can be fed conveniently into the side arm of the jet. Heated dry gas flowing at a high velocity horizontally through the jet propels the yarn therethrough and heats same as desired. Again, the yarn initially contacts the flowing stream of hot gas at an angle with respect to the directional flow of the gas. Upon leaving the exit end of jet the yarn is withdrawn at an angle with respect to the directional flow of gas as soon as it is expelled therefrom. This sudden angular removal of the yarn from the stream of gas can be accomplished by proper positioning of a guide, such as a driven thread advancing means or feed rolls 59 as shown which advances the yarn at a controlled reduced rate.

In accordance with a variation of the present invention, the thermoplastic filament yarn is subjected preferably next to a treatment in a hot aqueous medium in a relaxed or substantially relaxed condition. This operation further increases the bulkiness, crimpiness, and stretchability of the yarn. As shown, the yarn after being passed through the jet is laid by means of a traversing piddler 51 on a moving perforated endless belt 52 (in a zig-zag pattern) that passes through a cabinet 53 having steaming and drying zones or compartments, the steaming compartment being provided with means 54 for supplying live steam upwardly through the belt to the yarn and the drying compartment being provided with drying means 55, such as an array of drying lamps for drying the steamed yarn. It is to be understood, of course, that other apparatus arrangements can be employed for subjecting the yarn to hot aqueous media while under little or no tension.

For example, in another continuous treating operation the yarn is suspended in hot water flowing through a tube or the like and then dried without tension by suitable means such as in a drying cabinet in which hot air or other suitable drying gas at an elevated temperature is directed onto the yarn therein. Additionally the yarn can be steam treated and dried by being conveyed and suspended by a stream of steam and conveyed and suspended by a stream of drying gas. After being permitted to shrink fully in a hot aqueous medium, the yarn is dried and is taken up in an orderly manner. As illustrated, traverse guide 56 lays the yarn on a bobbin 57 surface driven by roller 58 to form a yarn package 60. In this embodiment it is seen that the filaments are thermally deformed and discomposed in a continuous manner by the action of the heated air flowing through the jet and thereafter are permitted to relax continuously in a hot aqueous medium. As indicated above, an advantage of this embodiment is that the yarn so treated has even greater bulkiness, crimpiness, and stretchability.

In accordance with this invention, it has been discovered that new and novel yarns having increased elasticity or stretchability, somewhat the appearance and many properties of spun yarn, are obtained speedily from continuous filaments made from thermoplastic resins. A useful, rapid, and economical method for making these new yarns comprises in general subjecting the continuous filament yarn to the action of a stream of high velocity hot gas, whereby the filaments are disturbed and thermally deformed into a bulky, voluminous, crimpy structure having excellent stability. A dry compressible gas is heated and compressed to a predetermined temperature and pressure. This compressed gas is supplied to and through a confined zone as in a jet above described, thereby establishing a stream of the gas flowing or flurrying through such a zone at a high velocity. A thermoplastic continuous filament yarn is introduced into the stream of gas so established. The movement of the gas through the Zone conveys the yarn therethrough. Owing to the elevated temperature of the gas, the yarn is heated to a temperature below the melting point of the thermoplastic resin from which the yarn is made and above the minimum temperature where if a twist were imparted and the yarn cooled in the twisted condition, the twist would be set. Immediately upon emerging from the exit of the confined zone, the path of travel of the yarn is changed abruptly with the yarn being withdrawn from the stream of gas at an angle, preferably at with respect to the directional flow of the gas. The yarn is fed into the zone at a first rate and taken up after the gas disturbance and thermal deformation of the filaments occur at a reduced second rate. Such adjustment of the rates with respect to each other allows slack to be in the running yarn while it is being subjected to the action of the gas. The yarn is cooled before being tensioned or taken up in package form, to stabilize the bulky, crimpy structure of the yarn. Ordinarily, passing the yarn a short distance through air will accomplish this. In some instances it may be prefered to cool the bulked yarn by running it over a cooling surface, such as a metal plate, bar, or the like adapted to remove heat from the yarn or by employing a fan or the like to blow air across the yarn before it is subjected to tension. An additional operation whereby the bulkiness of the yarn is further augmented includes subjecting the yarn to a hot aqueous medium while relaxed and then drying the yarn.

The method of the present invention is applicable to a wide variety of continuous filament yarns, the require ment being that the yarns be made from a thermoplastic fiber-forming resin. The yarns may be formed by known techniques from these resins, including melt extrusion, wet spinning processes, and dry spinning processes. As examples of fiber-forming synthetic polymers which are included in the thermoplastic fiber-forming resins may be mentioned polyethylene; polypropylene; polyurethane; copolymers of vinyl acetate and vinyl chloride; the copolymers of vinylidene chloride and a minor proportion of mono-olefinic compounds copolymerizable therewith, such amaze? as, for example, vinyl chloride; homopolymers of acrylonitrile, copolymers of acrylonitrile and a minor proportion of at least one mono-olefinic compound copolymerizable therewith and polymer blends containing combined acrylonitrile in a major proportion; copolymers of vinyl chloride and acrylonitrile; linear polyesters of aromatic dicarboxylic acids and dihydric compounds, such as polyethylene terephthalate; linear polycarbonamides such as, for example, polyhexamethylene adipamide, polyhexamethylene sebacamide; polymeric monoaminomonocarboxylic acids or their amide forming derivatives such as polymeric -amino caproic acid; and other fiber-forming thermoplastic polymers. Mixtures of such fiber-forming synthetic polymers can also be used. The process of this invention is applicable particularly for the treatment of yarn generically referred to as nylon, including nylon 66, nylon 4, nylon 6, nylon 610, nylon 11, and the like.

While the present process is suitable for treatment of yarn whose filaments have a normal cross-section such as that produced where a spinneret having circular shaped orifices is employed during the manufacture thereof, unusual novelty eifects may be obtained by subjecting yarns having a non-circular cross-section to the hot air disturbance. For example, when yarn composed of a plurality of continuous filaments having a body section and a plurality of slender fin-like sections or legs integrally joined to said body and radially disposed upon the surface of and extending longitudinally of the body, such as yarn of X- or Y-shaped cross-section, are subjected to the treatment in accordance with the instant invention, the resulting yarn has increased covering power, resiliency, and a crisp feel. The number of fins may be two, three, four, or more and yarns having the fins are prepared by conventional methods, such as by employing during spinning a spinneret adapted to produce filaments having the desired number of fins or legs. Examination of a yarn having a Y-shaped cross-section and a slight twist and having been subjected to the method of the instant invention reveals that the finned sections thereof have a helical or spiral twist directionally reversed in a random pattern along the length of the individual filaments. This observation of the spiraled and reversed twist of the individual filaments may be seen by reference to FIGURE 6 of the drawing, illustrating a single filament so twisted wherein the body portion is of substantially rounded cross section and wherein the fin-like sections have rounded tips and are parentheticaly curved between the tips and the body portion. It has been found that the bulked yarn having the non-circular cross-section is excellent for rugs. Rugs made therefrom are more resistant to matting.

Twisted yarn can be processed as well as untwisted yarn. However, it is preferred to start with a source of yarn which has zero twist or little twist, such as producers twist. Pretwisting of the yarn is unnecessary and for economic consideration preferably is avoided. The denier of the thermoplastic yarn can vary considerably, as well as the denier of the individual filaments, the ordinary deniers of commercially available yarns being completely suitable. Yarns having different compositions and deniers can be combined before being processed. Moreover, the yarns can be molecularly oriented or not molecularly oriented. However, it is preferred that the yarn be oriented before being passed through the jet wherein the stream of hot air is flowing. As indicated above, one embodiment of the instant invention includes imparting an orientation stretch shortly before the yarn is subjected to the hot air treatment. By following this sequence of steps, a bulked yarn may be obtained advantageously by only slight modification of existing yarn drawing m.- chines.

As stated above, the yarn is supplied to the jet considerably faster than it is withdrawn therefrom and taken up. Although variation in the overfeed of the yarn is possible, best results are obtained in practicing the present invention when the yarn is supplied to the jet at a linear rate between 35 percent and 75 percent faster than it is withdrawn therefrom, depending on such process variables as the weight of the yarn being treated and the percent increase in bulkiness accomplished by following the present process.

The gas pressure needed to impart bulkiness to the yarn in accordance with the present invention is dependent on many process variables. In general, it can be stated that owing to the cost of compressing gas one should operate near the minimum pressure consistent with the obtaining of the desired characteristics in the yarn. Higher pressures, for example, are required when higher yarn speeds and heavier deniers are employed. Typical air pressure requirements for the known jets are about 40 to pounds per square inch gauge or higher.

The temperature of the gas required depends upon many factors including the type of yarn, the yarn speed, and the type of jet. The temperature of the gas should be kept below the temperature at which the yarn would melt during the process and preferably below the temperature at which adjacent filaments would stick during the process. However, the temperature should be sufficient so that the yarn will be deformed or distorted by the action of the high velocity gas without undue filament breakage. As indicated above, a desired temperature is one at which if the yarn were twisted and cooled in the twisted condition, the twist would be set. Of course, this temperature varies depending upon the nature of the thermoplastic polymer from which the yarn is made. The length of time that the yarn is contacted with the heated compressed gas is an important consideration. For a given yarn speed, a more elevated temperature for the gas is needed where the distance through which the yarn is conveyed by the heated gas through the jet is short. Moreover, where higher yarn speeds are used, a more elevated temperature, of course, is required.

By employing the above-described apparatus and process, one produces a bulked, crimped, stretchable continuous filament yarn as illustrated in FIGURE 5 with such properties having excellent stability. Bulk refers to the relative volume occupied by a given weight of yarn. Hence, yarns having increased bulk, such as those pro duced in accordance with the present invention, have greater covering power and warmth owing to the increased lateral interfilament spacing of the yarn and therefore converts into a more voluminous cloth. Surprisingly, the average degree of interfilament spacing generally is uniform from the central to the exterior portions of the structure. The increased voluminousness of bulk of the yarn has excellent stability, that is to say that the yarn is capable of withstanding a radially inward pressure applied thereto without permanently being compacted and will resume its original voluminous condition upon re moval of such pressure. Crimped refers to the fact that the filaments contain many crimps, crinkles, and the like which bend in and out in a sinuous pattern along the length of the filaments and which may be in one or more planes. The crimps in the filaments of the present invention have a somewhat rounded apex or curved bends as distinguished from one that is pointed or angular. The crimps introduced by means of the present invention are surprisingly permanent. Stated another way, the crimps have the capacity of retaining their sinuated and curved form and ordinarily can not be removed unless subjected to extraordinary stress, such as where longitudinal tension is applied to the yarn at an elevated temperature. stretchable refers to the fact that the yarns produced in accordance with this invention are elastic and have the ability to accept a slight longitudinally applied stress and thereby to become easily extended to a considerable length without becoming permanently elongated. For example, the yarn can be elongated 20-25 percent or more from its untensioned or relaxed length and immediately recover from this elongation in the nature of the so-called stretch yarn.

As a result of relaxation in hot aqueous media such as hot Water or steam while under little or no tension several changes simultaneously occur which constitute an important adjunct to the present invention, both in the individual filaments and in the yarn comprised thereby. The yarn and filaments are shrunk longitudinally, whereby the yarn increases in diameter. The crimps and deformations which result from the disturbance by heated gas flowing at a high velocity are developed in amplitude and frequency by the relaxation. At the same time the yarn is rendered more stretchable. In the abovedescribed embodiment the relaxation is accomplished by steaming the yarn after the hot compressed gas disturbance while laid tensionless on a belt conveying means. Other methods of subjecting the bulked products to hot aqueous media while under little or no tension, however, can be adapted, such as by immersing the yarn in water at an elevated temperature of, say 95 C., in hank form.

The following is an example of the above-described method of producing the improved yarns and filaments of the present invention.

Example The filaments used as starting materials were prepared by melt spinning polyhexamethylene adipamide, the crosssection of which was Y-shaped. A yarn composed of 70 of these filaments each of which had been cold-drawn and had a denier of about 15 and a twist of 0.3 turn per inch was wound onto a bobbin for treatment. Apparatus equivalent to that in FIGURE 1 was used to treat the yarn.

A reservoir of compressed air was established by employment of an air compressor and storage tank assembly. The compressed air was passed over an electrically energized heating coil to increase the temperature thereof to 450 F. Next the air was passed through the longitudinal bore in a fluid jet as above described. The pressure of the air entering the jet was 60 pounds per square inch gauge, the air consumption being about 2.7 cubic feet per minute. The yarn was unwound for treatment from the bobbin by passing same through a pair of positively driven feed rolls, the rate of withdrawal being about 61 yards per minute. From the feed rolls the yarn was led to the side arm of the jet, the air passing through the jet assisted in the threading of the yarn therethrough. The yarn was passed through a pigtail guide that was horizontally spaced with respect to the exit end of the jet so that the path of yarn travel was changed substantially 90 as the yarn issued forth from the jet. The yarn was wound around a second bobbin which was surface driven by a roller. The linear takeup speed was about 41 yards per minute, the overfeed of the yarn to the jet thereby being about 49 percent.

A knitted fabric was produced from the yarn so treated. The resulting fabric was bulky and fluffy and possessed an esthetic appeal. Moreover, the fabric had strength far superior to fabric comparably made from spun nylon yarn and had a high heat insulating capacity and an elasticity that was markedly stable. The fabric may be repeatedly washed and dried without losing the bulky character thereof.

A close examination of the individual filaments revealed the legs or fins extending from the filament body along the length thereof followed a helical pattern that was reversed randomly from a counterclockwise direction to a clockwise direction.

By steaming the yarn under zero tension and then drying same, the yarn contracted in length considerably and accordingly increased in diameter. The yarn so treated was found to be uniformly bulky and at the same time 10 elastic with the crimps therein being well developed and the lateral spacing of the filaments being very uniform and pronounced.

From the foregoing it is seen that the advantages of the present invention are many. The method results in the production of yarns having desirable bulk and is broadly applicable to produce such yarns from a wide range of filaments manufactured from thermoplastic resins. The invention provides a simple, rapid, and economical method and apparatus for commercially producing uniformly processed continuous filament thermoplastic yarn having increased bulk and elasticity. The inherent properties of the yarn are such that they impart numerous, novel, and desirable properties in woven, non- Woven, and knitted fabrics. Yarns composed of noncircular cross-sections and processed in accordance with the present invention have increased resiliency and enhanced covering power suitable for rugs, carpets, and the like.

Many different embodiments of the invention may be made without departing from the spirit and scope thereof. For example, novelty effects may be imparted to the yarn by irregular or regular variations in the air flow and yarn speeds. A thermoplastic filament yarn may be bulked together with or combined with a yarn which is not thermoplastic such as regenerated cellulose. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments shown and described herein, except as defined in the appended claims.

What is claimed is:

1. A multi-continuous filament yarn made of a homo geneous thermoplastic polymer, having a stable crimpy flutfy bulky character and a pronounced lateral spacing of the filaments thereof, and being substantially free of filamentary loops, characterized in that the individual filaments thereof have individually and randomly reversed helical twist about their respective axes along their lengths and particularly characterized in that the filaments have a body portion of substantially rounded cross section and a plurality of slender fin-like sections integrally joined to the body portion and radially disposed upon the surface of and extending longitudinally of the body portion, said fin-like sections having rounded tips and being parenthetically curved between the tips and the body portion, the radial length of the fin-like sections being greater than the diameter of the body portion.

2. The yarn of claim 1 wherein the polymer is nylon.

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1. A MULTI-CONTINUOUS FILAMENT YARN MADE OF HOMOGENEOUS THERMOPLASTIC POLYMER, HAVING A STABLE CRIMPY FLUFFY BULKY CHARACTER AND A PRONOUNCED LATERAL SPACING OF THE FILAMENTS THEREOF, AND BEING SUBSTANTIALLY FREE OF FILAMENTARY LOOPS, CHARACTERIZED IN THAT THE INDIVIDUAL FILAMENTS THEREOF HAVE INDIVIDUALLY AND RANDOMLY REVERSED HELICAL TWIST ABOUT THEIR RESPECTIVE AXES ALONG THEIR LENGTHS AND PARTICULARLY CHARACTERIZED IN THAT THE FILAMENTS HAVE A BODY PORTION OF SUBSTANTIALLY ROUNDED CROSS SECTION AND A PLURALITY OF SLENDER FIN-LIKE SECTIONS INTEGRALLY JOINED TO THE BODY PORTION AND RADIALLY DISPOSED UPON THE SURFACE OF AND EXTENDING LONGITUDINALLY OF THE BODY PORTION, SAID FIN-LIKE SECTIONS HAVING ROUNDED TIPS AND BEING PARENTHETICALLY CURVED BETWEEN THE TIPS AND THE BODY PORTION, THE RADIAL LENGTH OF THE FIN-LIKE SECTIONS BEING GREATER THAN THE DIAMETER OF THE BODY PORTION. 